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Q: A moving car faces the wind in the opposite direction. What will be the work done by the wind on the car?
  • A. Negative
  • B. Zero
  • C. Infinite
  • D. Positive
Correct Answer: Option A - When a car in motion faces the wind in the opposite direction, then the force exerted on the car by the wind acts opposite to the displacement of the car. Therefore, the angle between the direction of the applied force and the displacement of the car is 180 °. Work done (W) = F. d cos 180⁰ [There cos180º=–1] W = -F.d So, the work done by air on the car will be negative
A. When a car in motion faces the wind in the opposite direction, then the force exerted on the car by the wind acts opposite to the displacement of the car. Therefore, the angle between the direction of the applied force and the displacement of the car is 180 °. Work done (W) = F. d cos 180⁰ [There cos180º=–1] W = -F.d So, the work done by air on the car will be negative

Explanations:

When a car in motion faces the wind in the opposite direction, then the force exerted on the car by the wind acts opposite to the displacement of the car. Therefore, the angle between the direction of the applied force and the displacement of the car is 180 °. Work done (W) = F. d cos 180⁰ [There cos180º=–1] W = -F.d So, the work done by air on the car will be negative